Which of the following reacts with `KMnO_(4)` but does not react with tollen.s reagent?

Options

A. `C_(2)H_(6)`
B. `CH_(4)`
C. `C_(2)H_(4)`
D. `C_(2)H_(2)`

Explanation

To solve the question of which compound reacts with KMnO4 but does not react with Tollens' reagent, we can follow these steps:

### Step 1: Understand the Reagents
- **KMnO4 (Potassium Permanganate)**: This is a strong oxidizing agent that can oxidize alkenes and alkynes, leading to a color change from purple to colorless.
- **Tollens' Reagent**: This reagent is used to test for aldehydes and some unsaturated compounds. It contains silver ions that can be reduced to metallic silver, forming a characteristic silver mirror or precipitate.

### Step 2: Analyze the Given Options
We need to evaluate the reactivity of each compound with both KMnO4 and Tollens' reagent. The options provided are:
1. Ethane (C2H6)
2. Methane (CH4)
3. Ethene (C2H4)
4. Ethyne (C2H2)

### Step 3: Check Each Compound
- **Ethane (C2H6)**:
- Does not react with KMnO4 (as it is an alkane).
- Does not react with Tollens' reagent.

- **Methane (CH4)**:
- Does not react with KMnO4 (as it is also an alkane).
- Does not react with Tollens' reagent.

- **Ethene (C2H4)**:
- Reacts with KMnO4 (as it is an alkene).
- Does not react with Tollens' reagent.

- **Ethyne (C2H2)**:
- Reacts with KMnO4 (as it is an alkyne).
- Reacts with Tollens' reagent (produces a silver precipitate).

### Step 4: Conclusion
From the analysis, we find that **Ethene (C2H4)** is the compound that reacts with KMnO4 but does not react with Tollens' reagent. Therefore, the correct answer is:

**Option 3: Ethene (C2H4)**

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